(Associated with Fig. 4, E and E′). IQGAP1 binds to and displaces formin (mDia1) at filament plus ends. Reactions contain: 1 μM actin monomers (10% Alexa 647 label), 5 µM PFN1, 1 nM 549-SNAP-mDia1(ΔDAD), and 1 nM 488-SNAP-IQGAP1 or 488-SNAP-IQGAP1(BAD). Panels show individual wavelengths and merge. Arrows indicate free plus-ends (gray), individual molecules of IQGAP1 (green) or formin (pink), or IQGAP1–formin complexes (white). Playback, 10 FPS. Scale, 2 μm.
